High Resolution Chronostratigraphic Constraints on Terminal Paleozoic Crises and Recovery in the Circum-Tethys Region

高分辨率年代地层对特提斯地区古生代末期危机和恢复的制约本研究计划旨在通过三叠纪生物地层和磁性地层时间尺度改进晚二叠世的标定，以加深对末期古生代环境和生物危机以及随后的中生代恢复的理解。改进的时间尺度对于现实地评估各种观察到的生物和古环境异常的原因及其相互关系至关重要，这些异常是这一过渡的特征。我们最初的放射性同位素年龄数据(U/Pb和Ar/Ar)与最近的研究不同，其中许多研究倾向于由火流星撞击导致的快速灭绝。尽管不能先验地排除P-T界线上或附近的影响，但必须考虑更渐进的情景，以及二叠纪末南中国和二叠纪-三叠系边界的西伯利亚大陆玄武岩大规模火山活动--可能与其他因素结合--与生物危机之间的因果关系。尽管从二叠纪晚期到三叠纪早期，可用的地质年代学数据大幅增加，但关键的问题仍然没有得到回答，将被解决：1)二叠纪-三叠纪界线上的全球生物地层对比如何同步，生物地层、地球化学、岩石地层和其他记录如何准确地进行对比？2)二叠纪-三叠纪界线上的陆地记录和海洋记录之间的时间关系是什么？3)早三叠世的生物恢复速度是多少？4)实验室之间的差异(无论是物理上的还是解释上的)是否破坏了高精度的二叠纪-三叠纪界线上的高精度U/Pb锆石年龄之间的差异？实际上，U/Pb锆石年代学作为显生界时间尺度方法的可靠性有多高？

ABSTRACTHigh Resolution Chronostratigraphic Constraints on Terminal Paleozoic Crises and Recovery in the Circum-Tethys RegionRoland Mundil, Kenneth R. Ludwig, Paul R. RenneThis research program is intended to improve the calibration of late Permian through Triassic biostratigraphic and magnetostratigraphic time scales towards an enhanced understanding of the terminal Paleozoic environmental and biotic crisis and subsequent Mesozoic recovery. Improved time scales are critical to realistic evaluation of the causes of, and interrelationships between, the various observed biotic and paleoenvironmental anomalies that characterize this transition. Our initial radio-isotopic age data (both U/Pb and Ar/Ar) are at variance with recent studies, many of which favor a rapid extinction caused by a bolide impact. Although an impact at or near the P-T boundary cannot be excluded a priori, a more gradual scenario and a causal relation between the massive continental basalt volcanism in South China at the end of the Permian and Siberia at the Permian-Triassic boundary - possibly in combination with other factors - and the biotic crisis must be considered. Despite the dramatic increase in available geochronologic data for the Late Permian through Early Triassic interval, crucial questions remain unanswered and will be addressed: 1) How synchronous are global biostratigraphic correlations across the Permo-Triassic boundary, and how precisely can biostratigraphic, geochemical, lithostratigraphic, and other records be correlated? 2) What are the temporal relations between terrestrial and marine records across the Permo-Triassic boundary? 3) What was the rate of the biotic recovery in the Early Triassic? 4) Do interlaboratory discrepancies (either physical or by interpretation) between high-precision U/Pb zircon ages for the Permo-Triassic boundary undermine the inferred extremely rapid chronology of extinction events? Indeed, how reliable is U/Pb zircon geochronology as a Phanerozoic time scale method?